standard devation

Question

Assume that a normal distribution of data has a mean of

25

and a standard deviation of

7.

Use the

68−95−99.7

rule to find the percentage of values that lie

below

4.

Answer 1

mean = 25

sd = 7

below 4?

3sd = 3x7=21

25-21 = 4

below 4 is 1-99.7)/2 = .3/2 = .15%